The Star-K writes:
If one ate pareve food that was cooked in a fleishig [=meat] pot, one is not required to wait six hours before eating dairy. However, one may not eat this food together with dairy or reheat it in a dairy pot. For example, if one cooked spaghetti in a fleishig pot he may eat cheese immediately after finishing the spaghetti. However, he may not eat the spaghetti with cheese or with other dairy products. He should also not reheat the spaghetti in a milchig [=dairy] pot.
(See footnote 15 there for a more lenient exception when the meat pot hadn't been used for meat for a while. A more stringent exception (unmentioned there) AFAIK is when the pareve food being cooked is sharp.)
Footnote 16 there says:
If he inadvertently cooked the spaghetti… in a dairy pot, a Rav [=rabbi] should be consulted.
- Where does the restriction on reheating the pareve food in a dairy pot come from: who says it's forbidden? (The Rama 95:2, for one, doesn't, AFAICT.)
- The footnote's saying to ask a rabbi seems to imply the permissibility of the food and/or pot depends on multiple factors: what are those factors?